Hello,
I have proposed a solution to this ticket:
https://trac.torproject.org/projects/tor/ticket/21830
This issue is more involved than it seems, as there are a number of places that the nsTransferable is initialized and used without a loadContext, and it's not clear that the information required can always be passed along with it (e.g. when Invoked via the JS DOM path).
That said, I think my proposal is better than what's there now, and am open to feedback/criticism of this method, as there may be configurations I'm not aware of (since I've only looked at this code for a couple days now).
Please advise.
Thanks, -Neill.